1. Field of the Invention
The present invention relates to a liquid transporting apparatus which transports a liquid and a printer.
2. Description of the Related Art
Generally, an ink-jet recording head which jets the ink from a nozzle to a recording medium such as a recording paper has been adopted in printers in which an image is recorded by discharging an ink on to the recording medium. However, in such ink-jet recording head, a channel structure and an actuator structure for generating a jetting pressure in the ink is peculiar and complicated, and therefore, there have been limitations on facilitating a size reduction of the recording head by arranging a plurality of nozzles highly densely.
Therefore, inventors of the present invention have proposed a new type of recording head in which a developing phenomenon (electrowetting phenomenon) is used, in which a liquid repellent property (wetting angle), on a surface of an insulating layer covering a surface of a certain electrode, changes when an electric potential applied to the electrode is changed (refer to Japanese Patent Application Laid-open No. 2005-288875 for example). This recording head includes a plurality of individual channels formed by a plurality of grooves. Moreover, an individual electrode is provided to each of the individual channels (bottom surface of the grooves), and further, the insulating layer covers a surface of the individual electrodes. Moreover, the ink inside the recording head is in contact with a common electrode, which is kept at a ground electric potential, and the ink is at the ground electric potential all the time. Furthermore, at an upstream side of the individual channels, a pump, which pressurizes the ink toward a discharge portion at a front end thereof, is provided.
Here, the electric potential of the individual electrode is a ground electric potential, and with no electric potential difference between the ink and the individual electrode, the liquid repellent property (wetting angle) on the surface of the insulating layer sandwiched between the ink and the individual electrode is higher as compared to a liquid repellent property of an area of the bottom surface of the groove, in which the insulating layer is not provided. Therefore, the ink cannot flow to the discharge portion crossing the surface of the insulating layer, and the ink is not discharged from the discharge portion. On the other hand, when the electric potential of the individual electrode is switched to a predetermined electric potential, an electric potential difference is developed between the ink and the individual electrode, and the liquid repellent property (wetting angle) on the surface of the insulating layer sandwiched between the ink and the individual electrode is declined (electrowetting phenomenon). As the liquid repellent property of the insulating layer is declined, the ink pressurized by the pump is capable of moving to the discharge portion, thereby wetting the surface of the insulating layer, and is discharged from the discharge portion. Moreover, since such recording head has a simple structure in which the individual electrode, the common electrode, and the insulating layer are formed on a surface of a substrate forming the individual channels, it is possible to reduce a size of the recording head.